Magnesium and calcium contents in CNS tissues of amyotrophic lateral sclerosis patients from the Kii peninsula, Japan.

To further elucidate the involvement of metals as a factor in the pathogenesis of amyotrophic lateral sclerosis (ALS) on the Kii peninsula of Japan, a well-known high incidence area of ALS with low calcium and magnesium contents in soil and drinking water, we determined concentrations of these metals in samples of central nervous system tissue taken from postmortem ALS cases. Calcium content was determined by neutron activation analysis and magnesium by inductively coupled argon plasma emission spectrometry. From 5 ALS cases and 5 neurologically normal controls, we examined tissues from the precentral gyrus, including the motor cortex, internal capsule, crus cerebri and spinal cord, and from 22 other areas. The average calcium content in precentral gyrus, internal capsule, crus cerebri and spinal cord in ALS cases was higher than that in the controls, and the mean value of all 26 areas in the ALS cases was also higher than that of the controls. The average magnesium content of each region as well as the mean value of the 26 regions in the ALS cases was significantly lower than that in the controls. The Ca/Mg ratio of the 26 ALS regions was significantly higher than that of controls. This study strengthens our hypothesis that an abnormal metal metabolism plays a responsible role in the Ca-hydroxyapatite formation observed in central nervous system tissue of ALS cases, leading to motor neuron death and degeneration of the pyramidal tracts.